05000529/LER-2005-002

LER-2005-002,

Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. 05000
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function
5292005002R00 - NRC Website

1. REPORTING REQUIREMENT(S):

This LER 50-528/2005-002-00 is being reported under 10 CFR 50.73(a)(2)(i)(B), Operation or Condition Prohibited by the Technical Specifications. Specifically, on May 16, 2005 at approximately 09:50 hours MST Unit 2 unknowingly entered a specified condition (reactor coolant system (RCS)(AB) pressure > 1837 psia) with Low Pressure Safety Injection (LPSI) pump 'A' that had a degraded mechanical seal,(EIIS: BP-SEAL). This is contrary to LCO 3.0.4 which precludes entry into a MODE or other specified condition in the Applicability statement when an LCO is not met. LCO 3.5.3 requires two Emergency Core Cooling Systems (ECCS)(BP) to be Operable in Modes 1, 2, and in Mode 3 when pressurizer.

(AB) pressure is greater than or equal to 1837 psia or RCS cold leg temperature is greater than or equal to 485 degrees Fahrenheit.

COMPONENT(S):

The function of the ECCS is to provide core cooling and negative reactivity to ensure that the reactor core (AC) is protected after certain accidents. Two redundant, 100% capacity trains are provided with each train consisting of High Pressure Safety Injection (HPSI)(BQ) and Low Pressure Safety. Injection (LPSI)(BP) subsystems. In MODES 1, 2, and 3, with pressurizer pressure greater than or equal to 1837 psia or with RCS cold leg temperature greater than or equal to 485°F, both trains.are required to be OPERABLE to ensure that 100% of the core cooling requirements can be provided in the event of a single active failure.

3. INITIAL PLANT CONDITIONS:

On May 17, 2005, Unit 2 was in Mode 3 (HOT STANDBY), at zero percent power.

There were no components or systems inoperable at the time of this event that affected this event other than the condition being reported.

4. CHRONOLOGY OF RELEVANT EVENTS:

On May 17, 2005, during plant startup, a leak was discovered at the LPSI pump 'A' mechanical seal. Upon discovery, the pump was declared INOPERABLE at 00:30 AM, MST. The pump had been shut down in MODE 4 (HOT SHUTDOWN) and subsequently, entry into MODE 3 was made. The Unit was in MODE 3 when the degraded seal condition was discovered.

On June 10, 2005, Me.chanical Maintenance Engineering determined the cause of the seal degradation was inadequate venting of the seal prior to one or more pump starts while the Unit was in MODE 5. Therefore, after the fact, there was no firm evidence that the I_PSI A pump was operable when applicable LCO 3.5.3 Mode 3, greater than or equal to 1837 psia conditions were entered on May 16, 2005, at 09:50 AM, a violation of Technical Specification 3.0.4.

Additionally, at the time of discovery, Unit 2 entered the appropriate Tech Spec LCO 3.5.3 and remained in Mode 3 until LPSI A was restored to service on May 18, 2005 10:20 PM a total of 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> and 30 minutes. This is less than the 7 days of inoperability allowed by LCO 3.5.3 Required Action A.1.

5. ASSESSMENT OF SAFETY CONSEQUENCES:

The condition did not result in any challenges to the fission product barriers or result in the release of radioactive materials. Therefore, there were no adverse safety consequences or implications as a result of this condition and the condition did not adversely affect the safe operation of the plant or health and safety of the public.

The condition would not have prevented the fulfillment of the safety function and did not result in a safety system functional failure as defined by 10CFR50.73(a)(2)(v).

The condition did not result in a transient more severe than those analyzed in the Updated Final Safety Evaluation Report Chapters 6 and 15. The condition did not have any nuclear safety consequences, or personnel safety impact.

6. CAUSE OF THE EVENT:

Apparent Cause: air accumulation in the seal flush water lines apparently interfered with the supply of water to the seal faces allowing the seal to overheat and degrade.

The seal assembly is supplied with high pressure, clean: cooling water through the 'flush port' in the gland plate (inboard of the seal faces). The flush port injection line is piped from the LPSI pump's cyclone filter which is external to the pump. The cyclone filter is a high point in the injection line and is vented by means of a valve (valve designator 2PSIAV997).

This valve vents the cyclone filter, the injection line, and the seal assembly. The injection lines were not blocked or obstructed, 'as they were verified the clear during the seal replacement.

The LPSI A pump was started six times between April 18, 2005 when the seal was replaced and May 17, 2005 when the evidence of leakage was observed in the pump room.

Prior to the first two starts, the pump was vented at valve 2PSIAV977, which is considered a vent point only addressed by procedure when bringing the pump out of a maintenance activity or at the discretion of the Control Room. Supervisor. It was not procedurally required to vent at 2PSIA977 and therefore not vented at that location prior to the next four starts creating the possibility that air entrained in the system accumulated in the cyclone separator while the pump was shut down and caused seal degradation during one or more of the last four pump starts. There is no evidence to conclusively indicate the observed degradation occurred with any single pump start.

The photograph on the following page illustrates the equipment discussed in this report.

PHOTO : Cyclone Filter / High Point Vent If the completed investigation report includes information which would substantively change the reader's perception of the event, an LER supplement will be submitted.

7. CORRECTIVE ACTIONS:

• A corrective maintenance work order (CM #2800334), was initiated for the leaking mechanical seal and the LPSI 'A' Pump was repaired on May 18, 2005. The mechanical seal was removed, disassembled, inspected, rebuilt, and reinstalled using in-house Mechanical Maintenance procedure 31MT-9SI01.

• CRAI #2819014 has been generated to,require Operations to vent the cyclone filter prior to each manual LPSI or Containment Spray (CS) (EIIS: BE) pump start.

8. PREVIOUS SIMILAR EVENTS:

There have been three previous similar licensee events reported in the last three years.

occurred when required reactor power instrumentation was not calibrated as required by surveillance requirements. The cause of the event was human performance error by control room licensed operators who did no rev.-.ogrgze the change in acceptance criteria when power was reduced below 80 percent.' percent rated thermal power without meeting the Limiting Condition for Operation (LCO) for Axial Shape Index (ASI). The cause was determined to be that control room operators had incorrectly interpreted a provisional note in procedures.

when a mode change occurred with a safety injection valve not in its required position.

Preliminary investigation results indicated the cause of the event to be cognitive personnel error.

The previously implemented corrective actions from these three previous events would not have prevented this occurrence from happening.